Our objectives are to synthesise, characterise, and study the chemistry and physical properties of pi-cation radicals, pi-anion radicals of porphyrins and metalloporphyrins, and to examine the roles that such species play in the biosynthesis, enzymatic functions, metabolism, and degradation of the naturally occurring porphyrin enzymes. A variety of physical techniques including magnetic circular dichroism (MCD), electron spin resonance (esr), resonant Raman Spectroscopy (RS) and electrochemistry will be employed. In addition to this, model porphyrins and porphyrin enzymes containing metals other than iron will be synthesised and studied.